1. Technical Field
The present invention relates generally to clutch arrangements for power tools such as rotatable drills and power screwdrivers. More particularly, the present invention relates to a clutch arrangement that may be rotated through an angle of 360 degrees.
2. Discussion
Modern power tools, such as drills and power screwdrivers, have become increasingly complex over the past several years and are now commonly available with clutch mechanisms having an externally-accessed adjustment mechanism that is selectively positionable between a plurality of adjustment positions so as to limit the torsional output of the power tool. One relatively common type of adjustment mechanism includes an annular collar that is coupled to the body of the power tool and which is rotatable to a plurality of detented clutch positions. Typically, these adjustment mechanisms provide five or more discrete clutch adjustment settings which incrementally increase or reduce the torsional output capacity of the power tool. While such adjustment mechanisms generally provide satisfactory control of the torsional output of the power tool, several drawbacks have been noted.
One such drawback concerns the manner in which the adjustment mechanism is changed between relatively a low setting and a relatively high setting. Often times, for example, much more torque is required for drilling a hole into a workpiece than is required for installing a screw into a hole formed into the workpiece. To properly use the clutch mechanism, the user of the tool must rotate the adjustment mechanism from the high setting, which is used for drilling, through a plurality of intermediate settings and into the low setting, which is used for installing the screws. Once a screw has been installed, the user must then rotate the adjustment through the intermediate settings and into the high setting prior to drilling another hole. When large numbers of holes are to be drilled and screws installed, this practice becomes extremely laborious and a relatively large amount of time is wasted simply in adjusting the adjustment mechanism through the intermediate positions.
Accordingly, there remains a need for an adjustment mechanism for setting the clutch of a power tool that can be adjusted between the highest and lowest clutch settings without the need for moving the adjustment mechanism through a plurality of intermediate clutch settings.
In one preferred form, the present invention provides an adjustment mechanism for a clutch. The adjustment mechanism includes an annular adjustment structure having an adjustment profile with a ramp section, a first adjustment segment, a last adjustment segment and a plurality of intermediate adjustment segments. The first adjustment segment is configured to correspond to a first clutch setting and the last adjustment segment is configured to correspond to a last clutch setting. The ramp section is positioned between the first and last adjustment segments such that the adjustment structure is rotatable between the first and last adjustment segments and between the last and first adjustment segments without engaging any of the intermediate adjustment segments.